One of the greatest risks to oil and gas production infrastructure is accelerated internal pipeline corrosion, particularly as a field ages and water cut rises. The production of oil and gas reservoirs present corrosive environments that place the internal metallurgy of process equipment (e.g., transport pipelines, flow lines, separation equipment), often constructed of mild carbon steel, at risk for failure. The rate of corrosion deterioration in oil and gas field equipment metallurgy is dependent upon production parameters such as oil/water ratio, fluid brine composition, temperature, pH, and the concentration of corrosive gases typically present in the reservoir formation, such as CO2, H2S, or combinations thereof.
In order to preserve the integrity of oil and gas infrastructure, corrosion inhibitors are typically added into the production fluids upstream of piping infrastructure intended to be protected. In general, corrosion inhibitors of this type protect the metal through formation of a passivation film on the metal surface. This passivation layer oil wets the metal surface, which in turn prevents contact of the metal from the corrosive nature of the produced reservoir fluids. Typically, corrosion inhibitor formulations of this type contain a variety of aliphatic organic surfactant molecules ranging from, but not limited to, amines, quaternary amines, imidazolines, phosphate esters, amides, carboxylic acids, or combinations thereof.
Often, organic thiol compounds are added in low concentrations to these corrosion inhibitor components to increase the effectiveness of the traditional corrosion inhibitor molecules. It is believed that these organic thiol molecules create a stronger passivation layer on the metal surface which also increases the persistency of the protective film. In most examples, the sulfur based component consists of a primary thio/mercaptan (e.g., 2-mercaptoethanol or mercaptoacetic acid). In some instances, however, such thiol based formulations may degrade at elevated temperatures (e.g., during storage at elevated temperatures) to release volatile sulfur-containing vapor/gases (e.g., mercaptans, sulfur dioxide, hydrogen sulfide, and/or carbonyl sulfide).
Despite the availability of corrosion inhibitors for use in the oil and gas industry, there still exists a need for improved compounds, compositions, and methods.